Animation of graphite and graphene, forms of the element carbon. Graphite is most familiar from its use in pencils. On an atomic level, it comprises flat sheets of carbon atoms arranged in a hexagonal array. Each of these sheets is just one atom thick. A single sheet of carbon atoms is known as graphene. Graphite is made up of many of these sheets stacked on top of one another. The bonds between the atoms in a sheet are much stronger than those between the sheets, meaning the sheets can easily slide over one another. It is this property that gives graphite its softness as a material, and makes it useful for writing. In an individual graphene sheet, some of the atoms' electrons (blue) are delocalised across the sheet, rather than being tightly bound to each atom. In both graphite and graphene, this property makes the material a very good conductor of electricity. When a voltage is applied, the electrons flow from negative to positive charge, which can create a circuit capable of doing electrical work, such as powering a light bulb.